Robert Zeldin has been appointed chief medical officer of Cambridge, MA, drug developer Acceleron Pharma (NASDAQ: [[ticker:XLRN]]). Zeldin joins Acceleron from Belgium-based Ablynx, where he was chief medical officer. Zeldin’s appointment comes as Acceleron and partner Celgene (NASDAQ: [[ticker:CELG]]) prepare to file for FDA approval of the drug luspatercept. The companies have released positive results from late-stage studies testing the drug as a treatment for two blood disorders, myelodysplastic syndrome and beta-thalassemia.